Portion of a shoe midsole



FIG. 1 is a first perspective view of a portion of a shoe midsole showing my new design;

FIG. 2 is a second perspective view thereof;

FIG. 3 is a side view thereof; and,

FIG. 4 is a rear view thereof.

The uneven broken lines immediately adjacent to the shaded area represent unclaimed boundaries of the design. The uneven broken line showing of the remainder of the shoe is for illustrative purposes only and forms no part of the claimed design. 

The ornamental design for a portion of a shoe midsole, as shown and described. 